lam supposed to recover a 60.0 ppm (parts per million) concentration of matrix spike after running an assay (procedure). I ran the assay 4 times and got concentrations of 42.6 ppm, 43.5 ppm, 41.9 ppm, and 42.3 ppm. Are my results accurate? Precise? Why?

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?